Sure thing! We've got 781 and we're gonna multiply it by 39. That's the same as adding 781 to itself 39 times.
Step 1: 0 + 781 = 781
Step 2: 781 + 781 = 1562
Step 3: 1562 + 781 = 2343
Step 4: 2343 + 781 = 3124
Step 5: 3124 + 781 = 3905
Step 6: 3905 + 781 = 4686
Step 7: 4686 + 781 = 5467
Step 8: 5467 + 781 = 6248
Step 9: 6248 + 781 = 7029
Step 10: 7029 + 781 = 7810
Step 11: 7810 + 781 = 8591
Step 12: 8591 + 781 = 9372
Step 13: 9372 + 781 = 10153
Step 14: 10153 + 781 = 10934
Step 15: 10934 + 781 = 11715
Step 16: 11715 + 781 = 12496
Step 17: 12496 + 781 = 13277
Step 18: 13277 + 781 = 14058
Step 19: 14058 + 781 = 14839
Step 20: 14839 + 781 = 15620
Step 21: 15620 + 781 = 16401
Step 22: 16401 + 781 = 17182
Step 23: 17182 + 781 = 17963
Step 24: 17963 + 781 = 18744
Step 25: 18744 + 781 = 19525
Step 26: 19525 + 781 = 20306
Step 27: 20306 + 781 = 21087
Step 28: 21087 + 781 = 21868
Step 29: 21868 + 781 = 22649
Step 30: 22649 + 781 = 23430
Step 31: 23430 + 781 = 24211
Step 32: 24211 + 781 = 24992
Step 33: 24992 + 781 = 25773
Step 34: 25773 + 781 = 26554
Step 35: 26554 + 781 = 27335
Step 36: 27335 + 781 = 28116
Step 37: 28116 + 781 = 28897
Step 38: 28897 + 781 = 29678
Step 39: 29678 + 781 = 30459

So, 781*39 = 30459